Digital cameras have prevailed rapidly, and personal computers (PC) are normally used at home. Images sensed by a digital camera are printed using a PC and a printer, and are published on a home page or the like. However, exposure and white balance of a digital camera are not always perfect, and image correction of an image is required before printing or publication in some cases. However, image correction requires experience, and the user who has little experience cannot desirably correct an image. For this reason, various automatic image correction methods have been proposed for inexperienced and unaccustomed users of image correction.
Automatic image correction is mainly done based on an analysis result such as the histogram of pixel values of an image. However, more appropriate image correction can be attained in consideration of meta data (additional information) in addition to information of an image itself. For example, image data compatible to Exif can record practical values such as a shutter speed, aperture value, and the like. Automatic image correction using such meta data is disclosed in, e.g., Japanese Patent Laid-Open No. 2001-202509. The invention described in this reference classifies noise reduction parameters according to the ISO speed, and determines parameters according to the ISO speed.
An image is not always sensed as a photographer intended. For example, an image which is darker than expected or an image which appears unsharp as a whole due to low sharpness by, e.g., camerashaking, is often obtained. When such an image is to be corrected, image processing software such as Adobe® PhotoShop® and the like can be used. Functions of PhotoShop® such as “brightness/contrast”, “tone curve”, “hue/saturation”, “color balance”, “unsharp mask”, “edge emphasis”, “blur”, and the like are applied to an original image in an arbitrary order to correct the image. For example, arbitrary correction functions can be applied at arbitrary timings by, e.g., applying “color balance”, applying “tone curve” to that result, and further applying “unsharp mask” to the result.
An image process applies various processes to an original image in turn. When a plurality of processes are applied in different orders, quite different correction results are normally obtained.
Since it is very troublesome to apply various correction functions, a method of presenting similar correction functions together in place of breaking up correction menu items may be used. Japanese Patent Laid-Open No. 11-345321 describes a method of presenting parameters associated with color tone correction to the user, and correcting a color tone in a predetermined order.
However, in any of the above methods, parameters of various processes having different characteristics such as noise removal, color tone correction, sharpness, and the like must be designated one by one in an application order. For example, when correction is to be applied in the order of noise removal, color tone correction, and sharpness, and noise removal parameters are to be changed, one of a method of applying noise removal to an image as a result of application of the three processes, or a method of redoing the above processes from the beginning after undoing all the processes must be selected. As the image process is applied repetitively, an image to be corrected suffers tone jump or the like. Hence, redoing these processes is basically selected. In other words, all the correction results are discarded, and correction processes are redone from the beginning.
Some printer drivers display a thumbnail image that reflects the effect of correction to be applied, or retouch software partially displays an image in an enlarged scale to provide a preview. However, the user cannot observe such image by freely changing the enlargement ratio or display size, and can hardly recognize an actual print result.